C :

#include <stdio.h>

int main(){
   int i,s = 0,n;
   scanf("%d",&n);
   for(i = 1;i <= n;i++){
      s = s + i;
   }
   
   printf("%d\n",s);
   return 0;
}

C++ :

#include <iostream>
using namespace std; 
 
int main(){
   int i,s = 0,n;
   cin>>n;
   for(i = 1;i <= n;i++){
      s = s + i;
   }
    
   cout<<s<<endl;
   return 0;
}

Java :

import java.util.Scanner;
public class Main{ 
//	public static void main(String args[]) { 

//public class demo1 {
	public static void main(String[] args) {
//		System.out.println("hello,word");
//		String string = "666";
//		System.out.println(string);
//		Random a = new Random();
//		System.out.println(string);
//		System.out.println(a);
		Scanner sc = new Scanner(System.in);
		int a = sc.nextInt();
//		int b = sc.nextInt();
//		System.out.println("ss" + a + b);
		int i = 0;
		int ba = 0;
		while (i <= a) {
			ba = ba + i;
			i = i + 1;
		}
		System.out.println(ba);

	}
}

Python :

n =  int(input());
s = 0;
for i in range(1,n + 1):
    s = s + i;
print(s);